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  * Author: Thomas E. Dickey
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<H1 class="no-header">new_pair 3x</H1>
<PRE>
<STRONG><A HREF="new_pair.3x.html">new_pair(3x)</A></STRONG>                                               <STRONG><A HREF="new_pair.3x.html">new_pair(3x)</A></STRONG>




</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
       <STRONG>alloc_pair</STRONG>,  <STRONG>find_pair</STRONG>,  <STRONG>free_pair</STRONG> - new curses color-pair
       functions


</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
       <STRONG>#include</STRONG> <STRONG>&lt;curses.h&gt;</STRONG>

       <STRONG>int</STRONG> <STRONG>alloc_pair(int</STRONG> <STRONG>fg,</STRONG> <STRONG>int</STRONG> <STRONG>bg);</STRONG>
       <STRONG>int</STRONG> <STRONG>find_pair(int</STRONG> <STRONG>fg,</STRONG> <STRONG>int</STRONG> <STRONG>bg);</STRONG>
       <STRONG>int</STRONG> <STRONG>free_pair(int</STRONG> <STRONG>pair);</STRONG>


</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
       These functions are an extension to  the  curses  library.
       They permit an application to dynamically allocate a color
       pair using the foreground/background  colors  rather  than
       assign  a  fixed  color  pair number, and return an unused
       pair to the pool.

       The number of colors may be related to the number of  pos-
       sible color pairs for a given terminal, or it may not:

       <STRONG>o</STRONG>   While  almost  all  terminals  allow setting the color
           <EM>attributes</EM> independently, it  is  unlikely  that  your
           terminal  allows  you  to  modify  the attributes of a
           given character cell without rewriting it.   That  is,
           the  foreground and background colors are applied as a
           pair.

       <STRONG>o</STRONG>   Color pairs are the curses library's way of managing a
           color  palette on a terminal.  If the library does not
           keep track of the <EM>combinations</EM>  of  colors  which  are
           displayed, it will be inefficient.

       <STRONG>o</STRONG>   For  simple  terminal  emulators with only a few dozen
           color combinations, it is convenient to use the  maxi-
           mum  number  of  combinations  as  the  limit on color
           pairs:

             <STRONG>COLORS</STRONG> <EM>*</EM> <STRONG>COLORS</STRONG>

       <STRONG>o</STRONG>   Terminals which support <EM>default</EM> <EM>colors</EM>  distinct  from
           "ANSI  colors"  add to the possible combinations, pro-
           ducing this total:

             <EM>(</EM> <STRONG>COLORS</STRONG> <EM>+</EM> <EM>1</EM> <EM>)</EM> <EM>*</EM> <EM>(</EM> <STRONG>COLORS</STRONG> <EM>+</EM> <EM>1</EM> <EM>)</EM>

       <STRONG>o</STRONG>   An application might use up to a few dozen color pairs
           to implement a predefined color scheme.

           Beyond  that  lies  in the realm of programs using the
           foreground and background colors for "ASCII  art"  (or
           some other non-textual application).

           Also  beyond  those few dozen pairs, the required size
           for  a  table  to  represent  the  combinations  grows
           rapidly with an increasing number of colors.

           These  functions  allow  a developer to let the screen
           library manage color pairs.


</PRE><H3><a name="h3-alloc_pair">alloc_pair</a></H3><PRE>
       The <STRONG>alloc_pair</STRONG> function accepts parameters for  foreground
       and background color, and checks if that color combination
       is already associated with a color pair.

       <STRONG>o</STRONG>   If the combination already exists, <STRONG>alloc_pair</STRONG>  returns
           the existing pair.

       <STRONG>o</STRONG>   If  the  combination  does not exist, <STRONG>alloc_pair</STRONG> allo-
           cates a new color pair and returns that.

       <STRONG>o</STRONG>   If the table fills up, <STRONG>alloc_pair</STRONG> discards the  least-
           recently allocated entry using <STRONG>free_pair</STRONG> and allocates
           a new color pair.

       All of the color pairs are allocated from a table of  pos-
       sible color pairs.  The size of the table is determined by
       the terminfo <EM>pairs</EM> capability.  The table is  shared  with
       <STRONG>init_pair</STRONG>; in fact <STRONG>alloc_pair</STRONG> calls <STRONG>init_pair</STRONG> after updat-
       ing the ncurses library's fast index to the colors  versus
       color pairs.


</PRE><H3><a name="h3-find_pair">find_pair</a></H3><PRE>
       The  <STRONG>find_pair</STRONG>  function accepts parameters for foreground
       and background color, and checks if that color combination
       is  already  associated  with  a color pair, returning the
       pair number  if  it  has  been  allocated.   Otherwise  it
       returns -1.


</PRE><H3><a name="h3-free_pair">free_pair</a></H3><PRE>
       Marks  the  given  color  pair as unused, i.e., like color
       pair 0.


</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
       The <STRONG>alloc_pair</STRONG> function returns a color pair number in the
       range  1  through  <STRONG>COLOR_PAIRS</STRONG>-1,  unless it encounters an
       error updating its fast index to the  color  pair  values,
       preventing it from allocating a color pair.  In that case,
       it returns -1.

       The <STRONG>find_pair</STRONG> function returns a color pair number if  the
       given  color  combination has been associated with a color
       pair, or -1 if not.

       Likewise, <STRONG>free_pair</STRONG> returns <STRONG>OK</STRONG>  unless  it  encounters  an
       error  updating the fast index or if no such color pair is
       in use.


</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
       These routines are specific to  ncurses.   They  were  not
       supported  on  Version 7, BSD or System V implementations.
       It is recommended that any code depending on them be  con-
       ditioned using NCURSES_VERSION.


</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
       <STRONG><A HREF="init_pair.3x.html">init_pair(3x)</A></STRONG>.


</PRE><H2><a name="h2-AUTHOR">AUTHOR</a></H2><PRE>
       Thomas Dickey.



                                                           <STRONG><A HREF="new_pair.3x.html">new_pair(3x)</A></STRONG>
</PRE>
<div class="nav">
<ul>
<li><a href="#h2-NAME">NAME</a></li>
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
<ul>
<li><a href="#h3-alloc_pair">alloc_pair</a></li>
<li><a href="#h3-find_pair">find_pair</a></li>
<li><a href="#h3-free_pair">free_pair</a></li>
</ul>
</li>
<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
<li><a href="#h2-AUTHOR">AUTHOR</a></li>
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